1. Field of the Invention
The present invention relates to a diaphragm-type valve which is connected to a gas storing cylinder, a piping or the like for gas of ultra-high purity to be used during the production step of semi-conductors or the like.
2. Explanation of Related Art
The gas of ultra-high purity to be used during the production step of semi-conductors needs such a high purity as not allowing the contamination of a little impurity and besides has a corrosive action and a flammability. As such, it has so particular a characteristic that it requires a minute attention when being handled.
There is a conventional example of the diaphragm-type valve used for the gas which is employed when producing semi-conductors or the like, disclosed in Japanese Patent Public Disclosure No. 62-270872.
The conventional diaphragm-type valve comprises a housing within which an inlet bore communicates with an outlet bore via an inlet passage, a shut off valve chamber and an outlet passage in the mentioned order. The inlet passage opens to the shut off valve chamber and has a shut off valve seat formed on a periphery of its open end. The housing is provided with a shut off valve attaching bore, within which the shut off valve chamber is formed. A thrust screw member, an intermediate transmission means and a closure member are attached into the shut off valve attaching bore in the mentioned order from an exterior. The shut off valve chamber accommodates the closure member. A diaphragm is arranged between the closure member and the intermediate transmission means. The diaphragm hermetically seals the shut off valve chamber. Further, the shut off valve chamber accommodates a valve opening spring, which resiliently pushes the closure member in a direction away from the shut off valve seat, namely in a valve-opening direction.
The conventional technique accommodates the valve opening spring within the shut off valve chamber. Therefore, the valve opening spring contacts with fluid which flows through the shut off valve chamber. Besides, the shut off valve chamber cannot be downsized because it has to secure a space for accommodating the valve opening spring, which results in contacting with the fluid in a large area. This entails a problem of being unable to easily reduce the contamination into the fluid of impurities generating from contact surfaces between the fluid and either of the shut off valve chamber and the valve opening spring.
Moreover, if the valve is used to result in wearing off and deteriorating the closure member and the other members, it has to be exchanged. On the other hand, a housing of a valve is generally formed from stainless material or the like which has an excellent anti-corrosiveness. Accordingly, it is expensive and in many cases wears off and deteriorates more seldom than the other parts. Then, when exchanging the valve, it is desired to reuse the expensive housing. However, the closure member, the diaphragm and the intermediate transmission means are made of separate members, respectively and therefore have to be removed from the housing independently. Further, when incorporating new parts, they must be assembled one by one to result in making the exchanging work of parts troublesome.
The present invention has an object to reduce contact area with fluid which flows through an interior area of the valve and to facilitate the exchanging work of the closure member and the like parts.
In order to accomplish the above-mentioned object, the present invention has constructed a diaphragm-type valve in the following manner, for example, as seen from FIGS. 1 and 2 showing an embodiment of the present invention.
The present invention comprises a housing 4 within which there are provided an inlet bore 6, an inlet passage 8, an outlet passage 10, an outlet bore 11 and a shut off valve attaching bore 16. The shut off valve attaching bore 16 has an intermediate transmission means accommodating space 25, a shut off valve chamber 9 and a shut off valve seat 20 formed in the mentioned order from an exterior of the housing 4 to an interior thereof. A thrust screw member 17, an intermediate transmission means 18 and a closure member 19 are attached into the attaching bore 16 in the mentioned order from the exterior. The shut off valve chamber 9 communicates with the inlet bore 6 through the shut off valve seat 20 and the inlet passage 8 as well as with the outlet bore 11 through the outlet passage 10. The shut off valve chamber 9 accommodates at least part of the closure member 19. Arranged between the intermediate transmission means 18 and the closure member 19 is a diaphragm 21, which partitions the shut off valve attaching bore 16 into the intermediate transmission means accommodating space 25 and the shut off valve chamber 9, and hermetically seals the shut off valve chamber 9. Disposed in the accommodating space 25 is a valve opening spring 29, which resiliently urges the intermediate transmission means 18 in a direction away from the shut off valve seat 20.
The present invention functions as follows.
When a handle or the like rotating portion connected to the thrust screw member rotates the thrust screw member in a tightening direction, the thrust screw member spirally advances to produce a thrust. The intermediate transmission means which has received the thrust pushes the closure member through the diaphragm against a resilient pushing force of the valve opening spring. As a result, the closure member moves toward the shut off valve seat and comes into contact with the shut off valve seat to close the valve.
On the other hand, when the rotating portion is rotated in a loosening direction, the thrust screw member retreats to remove the thrust added to the intermediate transmission means. As a result, the intermediate transmission means is resiliently pushed in a direction away from the shut off valve seat by the resilient pushing force of the valve opening spring and the closure member fixed to the intermediate transmission means separates from the shut off valve seat to open the valve.
If the valve is used to result in wearing off the closure member and the other members or the like, it has to be exchanged. In the case where the housing is reused when making this exchange, a cap bolt and the like which fixes the thrust screw member is removed to take the respective parts out of the shut off valve attaching bore. At this time, the intermediate transmission means, the diaphragm and the closure member are mutually fixed. Therefore, they are easily handled as one unit. As for the housing from which the respective parts are removed, confirmation is made to see the housing does not suffer from a large wear or the like. And after having removed a likelihood of generating impurities, by washing and the like according to the need, new parts are incorporated into the shut off valve attaching bore. Also at this time, new closure member, diaphragm and intermediate transmission means are assembled into one set of unit. Accordingly, the respective parts are easily incorporated into the shut off valve attaching bore.
The present invention is constructed and functions as mentioned above and therefore produces the following advantages.
(1) The valve opening spring is arranged in the intermediate transmission means accommodating space and the shut off valve chamber accommodates only the closure member. This removes a probability that fluid which flows through the interior area of the shut off valve chamber contacts with the valve opening spring. Besides, there is no necessity of providing a space which accommodates the valve opening spring within the shut off valve chamber. Therefore, the shut off valve chamber can be formed into a small space, which results in the possibility of reducing a contact area with the fluid which flows through its interior area. This can decrease the contamination of impurities which generate from the valve, into gas of ultra-high purity.
(2) Since the closure member and the intermediate transmission means are fixed to one another through the diaphragm, they can be handled as one set of unit. As a result, in the case where the closure member and the like wear off or deteriorate, it is possible to easily effect the exchanging work such as removal and assembling of these parts.
It is sufficient if the intermediate transmission means and the closure member are fixed to each other through a diaphragm while the diaphragm is maintaining to hermetically seal the interior area of the shut off valve chamber. The fixing structure is not limited to a specific one.
For instance, the present invention includes the following diaphragm-type valve.
One (the closure member 19) of the intermediate transmission means 18 and the closure member 19 is provided with a projection 19b, to which the other 18 is fixed. And the diaphragm 21 is provided with an insertion hole 26 into which the projection 19b is inserted and with an inner peripheral wall portion of a peripheral edge of the insertion hole 26. The inner peripheral wall portion of the diaphragm 21 is hermetically fixed to at least one of the intermediate transmission means 18 and the closure member 19. It can be hermetically fixed by welding.
It is preferable to form the projection on the side of the closure member and project it toward the intermediate transmission means accommodating space rather than toward the diaphragm. In this case, the shut off valve chamber can have its interior area downsized to result in reducing the contact area with the fluid much more.
The present invention also includes the following diaphragm-type valve.
The thrust screw member 17 has an inner end provided between itself and the intermediate transmission means 18. The inner end is formed with a curved surface which projects inwards. In this case, a rotational force is hardly transmitted to the intermediate transmission means, but only the thrust is satisfactorily transmitted thereto when spirally advancing the thrust screw member.
In addition, a sheet is interposed between the thrust screw member and the intermediate transmission means. Also in this case, the rotational force is hardly transmitted to the intermediate transmission means, but only the thrust is satisfactorily transmitted thereto when spirally advancing the thrust screw member. In this case, if the inner end of the thrust screw member 17 is formed with a curved surface, the rotational force is more hardly transmitted to the intermediate transmission means and therefore it is more preferable.
The valve opening spring is sufficient if it is arranged in the intermediate transmission means accommodating space and resiliently urges the intermediate transmission means in a valve-opening direction. It need not be attached by a specific and limitative structure.
For example, the present invention includes the following diaphragm-type valve.
The diaphragm 21 is formed with an outer peripheral portion. A cylindrical push sleeve 22 is arranged around the intermediate transmission means 18 and pushes the outer peripheral portion of the diaphragm 21 to hermetically seal the shut off valve chamber 9. The push sleeve 22 is provided with a spring retainer 27 and the intermediate transmission means 18 is formed with a spring presser 28. The valve opening spring 29 is attached between the spring retainer 27 and the spring presser 28. If constructed like this, the valve opening spring and the push sleeve can be assembled with the intermediate transmission means, the diaphragm and the closure member into one unit.
More specifically, the push sleeve arranged around the intermediate transmission means pushes the outer peripheral portion of the diaphragm and therefore is not removed from the diaphragm side. On the other hand, the valve opening spring is attached between the spring retainer in an inner surface of the push sleeve and the spring presser in an outer surface of the intermediate transmission means. The valve opening spring resiliently pushes the intermediate transmission means in the valve-opening direction. Thus the push sleeve arranged in the intermediate transmission means accommodating space is resiliently pushed in a valve-closing direction, namely toward the diaphragm by a reaction force of the valve opening spring. As a result, while the intermediate transmission means and the diaphragm are mutually fixed into an integral structure, the push sleeve cannot be removed therefrom as well as the valve opening spring. Accordingly, as for the valve having this structure, it is possible to more readily effect the exchanging work of parts because the valve opening spring and the push sleeve can be assembled with the intermediate transmission means, the diaphragm and the closure member into one unit.
It is more preferable to form a linear guide in the shape of a vertical groove between the intermediate transmission means and the push sleeve. This can assuredly prevent the rotation of the intermediate transmission means, thereby transmitting only the thrust of the intermediate transmission means to the diaphragm. This results in the possibility of inhibiting a torsion force from being added to the diaphragm and lengthening the lifetime of the diaphragm.